Identification and monitoring of organic compounds in the parts per million range in industrial atmospheres, for example, commonly involves adsorbent techniques and gas chromatography. Organics are removed from adsorbents such as charcoal, porous polymers or the like either by solvent extraction or preferably by evaporation when thermal stability permits. Because adsorbed test samples often do not consist of a single material and even after adsorbent concentration are still in the submilligram range, gas chromatography is used to make the necessary separation. Positive identification of the resulting gas chromatographic peaks is normally made through the use of a directly coupled mass spectrometer.
In the best prior art practice, a sample tube containing an adsorbed sample is coupled into a carrier gas loop external to the gas chromatograph--mass spectrometer assembly and heated in a suitable oven to accomplish quantitative transfer of the adsorbed organic material of interest to the head of the gas chromatographic column. This procedure involves certain substantial difficulties, however, including the exclusion of air, which is an essential requirement of any mass spectrometry operation. In addition, such installation and removal of the sample tubes in the system is time-consuming, as is the oven heating and cooling cycle, and the sealing problem is aggravated by the necessity for frequently opening and closing the external carrier gas loop as sample tubes are coupled and uncoupled in it.